Coded track circuit signaling system



Jan; 9, 1945. M. A. scHEG CODED TRACK CIRCUIT SIGNALING SYSTEM W ww 1 lif 36 u 29m En l E? R L Tn-, pxm .Kmm ll r 3323?@ @EL newm Y n u nmsvalrmm M IL u n v mm. Nm.. vmno udpcob v umwv M u ISB @EL En ,JM JW IL I L I L L .u o2 )v vou n. wxvmm IS@ N .O h- E ,IFT

O/H. 1. d :0.5000 N :05u90 .MJU-l,

Patented Jan. 9,1945

. CoDED TRACK CIRCUIT siGNALiNG SYSTEM Marcian A. Scheg, Rochester, N.Y., assigner to General Railway Signal Company, Rochester,

Application March 31, 1942, Serial No. 436,938

10 Claims.

lThe present invention relates to railway signaling systems of the codedtype and more particularly to a cut section for such systems wherein thecode impulses received at the entrance end of a particular section arerepeated into the exit type it is at times necessary to divide aparticular y block into a plurality of sections each section of whichhas its own track circuit including its own track source and track relayI'his is sometimes necessary because the blocks are longer than thelongest operable track circuit and at other times is necessary becauseballast resistances are extremelylow and changeable. If a block of acoded signaling system is divided into sections the code imuplses of onesection may be directly repeated into the section next to the rearWithout first decoding the impulses of the code and then applying anewly generated code to the track circuit in the rear. If, however, theimpulses of a code of one track are repeated into the track -circuitneXt in the rear it is important that the apparatus for so repeating thecode impulses be of a construction to reproduce the codeimpulses withouteither prolonging or decreasing their duration, be-

cause if either the impulses are prolonged or are made shorter thedifference will become accumulative from section to section so thateventually the track circuit may be either continuously energized orcontinuously deenergized depending upon Whether the impulses becameprogressively longer or shorter, respectively. This would of .courserender the system impracticable and probably inoperative.

Another problem that the signaling engineer is repeatedly confrontedwith is to transmit signal information in a direction opposite to thatin which the usual track circuit transmits information. That is, thetrack circuit-ordinarily transmits information from the exit end towardthe entrance end of the track section whereas it is In View of theforegoing and other important considerations it is proposed inaccordance with the present invention to create inverse code impulses inresponse to the operation of a code following track relay and tofurthermore repeat impulses into the next track `circuit in the rear inresponse to the operationof such code following track relay through themedium'of the same apparatus. In this connection it may be pointed outthat the repeated impulses must be of the same duration as thereceivedimpulses whereas the inverse code impulses must be of muchshorter duration and it is proposed to perform this function through theVmedium of the vsame apparatus in spite of the fact that these impulsesto be applied by the same apparatus must be of `different, durations.

Itis proposed in accordance with the present invention to employ a trackrepeater relay which has pick-up and drop-away characteristics such thatthe duration of front contact closure corresponds substantially to theduration of the code impulse in the track circuit which caused suchclosure, It is further proposed to employ an impulsing relay which isactuated in one direction through a circuit including a back contact ofthe code following track relayr and a front contact of the codefollowing track repeater relay and which is actuated back to itsoriginal position by selfactuation, that is, by a circuit including onlyits own contacts, this return actuation being specially and appreciablyretarded. I

Other objects, purposes and ycharacteristic features of the presentinvention will in part be described hereinafter and will in part beobvious` 'have been illustrated, the block M being dividedv intosections l and 2 by insulating joints I2. Each of the various tracksections is provided with a track lcircuit including a track battery Band a track relay TR; the track battery for the section 2 of block Mhaving been designated B2 and the track batteryA for the section l ofthe block M having been designated B1. At the entering end of each tracksection is provided a code following track repeater relay TP and animpulsing relay IM, this apparatus having for convenience beenillustrated only for the section 2 of the blockM. As illustrated, theentrance end of the section 2 of the block M is also provided with -aninverse code battery IB which may supply code impulses to the entranceend of the track circuit during off periods of the driven code foractuating the inverse code track relay ITR located at the exit end ofthe section 2 of block M.

Although the track relay TR has been illustrated as a neutral relay thisrelay is preferably polarity responsive in order to render this relaymore sensitive and, in order to prevent this relay responding to thecondenser effect of the track circuit or the inductive kick of the trackcircuit, as conditions may require, due to the inverse code limpulsewhich is applied to the entrance end of the track circuit just beforethe code following track relay TR is connected thereto, all in a mannerand for reasons more specifically pointed out hereinafter. This trackrelay 'IR although it is inherently quick acting is somewhat slow infollowing the code impulses on the track circuit because the codeimpulses received are weak and this code following track relay issomewhat slow dropping by reason with its connection in multiple withthe ballast of the track circuit as a result of which this ballast mayact as a retarding circuit so long as the track relay is connected tothe track rails. In other words, the code following track relay TR isslightly slow picking up and is slow dropping to substantially the sameextent.

Track repeater relay TP has a resistance unit 'r1 in multiple therewithto render this repeater 'relay slightly slow acting in response to bothenergization and deenergization thereof. In other Words, this repeaterrelay TP is slightly slow picking up and is slightly slow dropping. Thisrepeater relay TP has been made slightly slow dropping in order that itsfront contact I will be maintained closed long enough afterdeenergization thereof so Vthat the impulsing relay IM.Will respondduring the drop away time of this code following track repeater relayTP, the impulsing relay IM being actuated to its right-hand positionthrough a circuit including the back contact I4 of the code followingtrackrelay TR and the front contact I5 of the code following trackrepeater relay TP. The pick-up period of the track repeater relay TP issubstantially the same as the drop-away period of this relay so that theduration of closure of its front contacts I5 and I6 correspondsubstantially to the duration of the driven code impulses applied to thetrack circuit with which this track repeater relay `is associated. Fromthis it is readily seen that the code repeated bythe contact I6 of thetrack repeater relayTP from the section 2 into the section I next in therear thereof has impulses of substantially the same duration as theimpulses of the driven code from which they were repeated.

The impulsing relay IM is a polar relay of the mag-stick type which isprovided with an upper actuating winding and a lower returning winding,which windings have associated therewith relay retardinginstrumentalities whereby the relay is very quickly operated from itsleft-hand to its right-hand position upon the closure of an energizingcircuit for the actuating winding of the relay, but is very slowlyactuated from its righthand to its left-hand position upon energizationof the returning winding (bottom windingi of the relay. Referring toFig. 1 it will be observed that the returning winding has in multipletherewith a resistance unit r2 which may in combination with this bottomwinding constitute a slug for the relay toretard its response to theapplication of current to either winding of the relay. The retardingaction of this resistance r2, is however, slight and only retards theoperation of the relay to a small extent. The upper or actuatingwinding, onthe other hand, is provided with a rectiiier R and aresistance unit r3 of comparatively low resistance. In other words, theupper winding of this impulsing relay IM is slugged, or retarded, to amuch greater extent than is the lower winding of this relay but theretarding feature for the upper winding of this relay functions only toperform its retarding function when the magnetic flux in the relay isincreased in a particular direction or is decreased in the oppositedirection thorugh the core. In other words, if the actuating winding ofthe relay is energized as through back contact I4 of relay TR and frontcontact I5 of relay TP the impulsing relay IM is only slightly retardedin its response, this retardation being performed by the resistance unitr2 connected across the lower winding of the relay; whereas if the lowerwinding of the relay is energized through the medium of the contact 20assuming its right-hand position to produce magnetic flux of theopposite magnetic polarity the impulsing relay is retarded by both theresistance unit 'r2 and by the resistance unit r3 in series with rectierR. In other words, the impulsing relay IMl is lightly retarded in itsactuation when it is moved from its left-hand t0 its right-hand positionbut is heavily retarded when it is actuated from its right-hand positionto its left-hand position as a result of which the inverse impulsestarts very quickly after deenergization of the code following trackrelay TR and is prolonged for an appreciable time thereafter.

It should be observed that the retarding resistance 12 is effective wheneither of the two windings of the relayis energized or deenergizedwhereas the retarding resistance r3 and rectifier R are only effective`during deenergization of the circuit for the upper winding and duringenergization of the lower winding of the relay. In other words, arelatively long delay in the starting of the movement, of the armatureof the relay IM takes place upon energization of the lower winding butvery little such delay takes place upon energization of the upperwinding, it being remembered that these windings when energized areenergized to produce magnetism of opposite magnetic polarities in therelay.

In discussing the operating characteristics of this relay IM further itshould be understood that the primary purpose of the shunting pathincluding resistance r2 is to retard the collapse of the flux in therelay structure upon opening of the circuit for the lower winding inorder that the retained ilux be of sufficient magnitude and retainedlong enough to assure completion of the stroke of the relay armature andthe movement of the contacts from right to` left. Thisshunting pathincidentally also causes a very slight retardation in the building up ofthe iiux in the relay when the upper Winding is energized through itsenergizing circuit. This latter effect is undesirable in that it retardsthe speed of operatio-n of the contacts from left to right uponenergization of the upper winding of the relay but this undesirableretardation is entirely overcome by making the energizing circuit forthe upper windinga quick acting circuit by having a lowreactance-to-resistance ratio.

In order to greatlyV retard theoperationoi the 'relay contacts-frpmright Vsto left the path :iu-

'cluding resistance rinmultiple'with theupper winding of'thisrelayincludes .a rectifier which permits demagnetizing lcfurren'tlto l:flow upper winding 'when the lower is energizedf as well as whenthe-upper windingis--deenergized.v This rilow of. demagnetizing currentwhen the lower winding is energized.caiusesV retardation. of movementoftheamature .and contacts from fright. tofleft .and .this liow ofcurrent duer to deenergizationof kthe upper `winding cause. retention'of the `long enough to assure, .completionofthe stroke of the armature4in its vmoveintent 'from leftfto right. Not enlyis the 'series'resistance r4' employed to overcome f the armature .movement-retardingeltect above mentioned, but it is also employedfto greatly. 'increasethe speed of `movementzof. the armature and contacts of the relayfrlomleft to right. It

' is of course understoodA that the inclusion of the resistance r4 inthe,circuit for the 'upperwinding in itself `does not increase the speed`of buildup `oi current in thiswinding unless-this accompanied withV theapplication ofV a proportionally higheryoltage. The-ohmic value offtheresistance r3 is so chosen as produce 'the proper delay inA thestartingof movement of the armature y.and contacts from' right to 'leftto produce "the proper duration of inverse code impulse.

' l0pemticm'r--Letfus'assume that the coding rey ylay CR' in response tocontrol bysc'oder CI'i picks rup to apply a drivenv codeimpulse 25 ofthe-^180 impulses per minute' rate tothe. exit-end of the track circuitVfor'section-.il'of `block M. This code impulse'25 (see line of Fig;yBillcws from ythe positive lterminal. ciVU the track `battery B2, frontcontact` 35 'of 'coding relay' CR,y along the lower rail l through thecontact 2| of the impul'sing relay IM assuming its left-hand.positionand l through the code following track relayTR back throughY theupper rail, In to' the negative terminalof the track battery B2.Drivencode imlag in the vvdashes inline 3 as compared with the clashesin linef2 of Fig. 2 o-fthe drawing. This delay is in part dueto theshouting effectyupon the rela-y Winding producedby the track ballastresistance. f

Closure or the front contact |4-of the code following track relay TR?closes an energizingk circuit for vthe track` repeater relay Thiscauses. an impulse of Vcurrent tonow (see dashes lin line 5-01' Fig; 2lVinthe track repeater relay- TP in time phase-with the closure of.frontcontact"y I4 of relay TR. .(seedashes in line 3 of Fig. 2). This`trackrepeater relay TPis slightly. slow `acting andits frontcontacts'rl5 and I B will not closefuntilfashort timeafterfenergizationof its winding as shown by theotl-set in the dashes in.line Bof Fig. Zas comparedwith the dashes in line 5 of this zgureofrthedrawing. f V v Upon cessation of.y the impulse of the driven code (linesand '2-ofFigf. 2) the track relay TR' will drop its contact Mland' willclose an enerigizing. circuit througnback contact |4- of this relay TRandthrough'front-'contactl5 of the track repeater relay TP resulting inthe closure vor an energizing circuit for the `.upper winding oftheimpulsing relay IM as shown by the dashes line -8 :of Fig. 2. Itwill benotedfthat these dashes (line 8- of .Fi-g. 2) Start .at .the point intime when the back contact oi.A ythe .trackrelay TR closes asillustrated inline All Aof Fig-2 as emphasized by the .dotted line 23,the maximum duration of the impulse `applied to the irnpulsing `relay IMterminating when the front ycontact I5 of the track repeater relay TPopens .as illustrateoly by the end lof .the dash in line 6 and `soemphasized by the dotted line 24. Since, however, the impulsing vrelayIM is very quick actin-g and since its energizing circuit may ybeselfinterrupted by the openingof its own Ipolar contact` the period ofenergization of .the impulsing relay IM is in `practice somewhat shorteras illustrated by the dotted line 21.

As .soon as the impulsing relay IM has koperated its'contacts 20 and 2|tothe right-hand posi- `'pulses 2.5.l have-beenv` illustrated inline 'lyof Fig. 2

v3| are of the rsame lengths.

the impulses repeatedbythe apparatus shown tion, which occurssubstantially simultaneously.

with the opening of these contacts in movement from their left-handposition as signiied bythe dotted line 21, the a1: plic`a'tion of aninverse code impulse to the track circuit, as illustrated bythe squaredotted lobes 26 in line l. of Fig. `2, :begins. Also, as soonl as theiinpulsing relay IM assumes its right-hand position a local energizingcircuit through its lower winding and its right-hand vcontact 20 isestablishedv vas 'indicated by the dash in line yIl) of Fig. 2. Thisapplication of current to the lower-'winding of relay IM is of the Asameduration and occurs simultaneously with the impulse kof the inverse codeapplied by the con-tact 2| to the trackcircuit of section 2, vasillustrated by the dotted inverse code lobe 26 in line and the dashy inline ofl Fig. 2 of the drawing.

It will be observed from the time chart of Fig. 2 Vthat theimpulsingrelay IM `remains in its right'- hand position much longer than in itsleft-.hand position. This is by reason of the fact that both of thewindings of the relay produce a retarding effect when the lower windingof the relay is energized whereas only the lower winding produces aretarding effect when the upper winding is energized, and also becausethe retarding' effect of the upper winding ismuch more pronounced. Thisfeature will cause the inverse impulse to be of substantial duration butwill cause it to occur very quickly after the driven impulse has ceased.This is important because the time interval between the driven impulseand the inverse impulse is lost time and should be as as possible.

The last line H of Fig. 2' illustrates the duration. of time, during thetransmission of a impulse per minute code, in which the contacts 20 and2| of the impulsing relay IM assume the left-hand position. It will beobserved that left contact 2| is closed .during the entire period of thedriven code impulse with ample margin. Also, from the parallelogramillustrated in Fig. 2'

of the drawing comprising the dashes 3|!` and 3| y in lines 2 and 5 ofFig. 2 connectedby dotted lines 32 and 33 it will be seen that thedashes Scand This signifies that at the entrance end'to section 2 ofblock M from this section into the exit end of section lof this block Mare of the same duration as the driven impulses flowing in the trackcircuit of the section 2. In other words, the driven code is reshort ypeated from the track circuit of the section 2 into the track circuit ofthe section I without material modication of the duration of itsimpulses. This is necessary where codes are repeated a number of timesto prevent the repeatedirnpulses from eventually getting too long or tooshort to be effective.

The same apparatus of applicants invention it will be observed is usedfor repeating a driven code from one track circuit into the next trackcircuit in the rear and is also used for producing inverse code impulseswhich are of much shorter duration and which lit into the o y periodsbetween the impulses of the driven code.

It should be understood that if desired the entrance end of the sectionI of block M may be provided with apparatus similar to that shown at theentrance end of section 2 and that this apparatus may bed used tocontrol decoding apparatus for manifesting Whether the transmitted codeis a 180 impulse, a l2() impulse or a 75 impulse per minute code. Thisdecoding apparatus when used is preferably controlled through the mediumof the front contact I'I of the track repeater relay TP for theparticular track circuits where devices are to be distinctivelycontrolled inl accordance with the code received.

The inverse code impulses, which are produced by the contact 2l of theimpulsing relay IM assuming its right-hand position intermittently asillustrated by the dotted lobes 26 in line I of Fig. 2, reach theright-hand or exit end of the section 2 at the time when the contact 35of the coding relay CR assumes its deenergized position. This is trueirrespective of whether driven codes of 180, 120 or '75 impulses createdby coding contacts CTI, CT2 or CT3,'respectively, are transmitted. Theseinverse code impulses are therefore applied to the slow dropping inversecode track relay ITR` and result in continuous ener- 40 gization of thisrelay ITR in spite of theintermittent nature of the code impulsesreceived. This inverse code following track relay ITR may, as throughthe medium of its contact 36, control approach lighting circuits for asignal located atj-.i'5

code has been received; may be used to generate;

an inverse code the impulses of which fall into the ofi periods of thedriven code and which inverse impulses are of considerably shorterduration and which apparatus may also be used for repeating theIimpulses of the driven code into the next track circuit in the rear in amanner to create impulses of the same duration as are the drivenimpulses of the code repeated. This apparatus includes a quick actingtrack relay TR,

' a rather quick acting track repeater relay TP and an impulsing relaywhich is controlled through a back contact of the track relay and afront contact of the track repeater relay and which impulsing relay isvery quick acting in operating to itsinverse-code position but is ratherslow acting t in returning to its driven-code-receiving position and inwhich the impulsing relay is self-actuating insofar as its return to itsdriven-code-receiving position is concerned.

It may be pointed out here that the impulsing relay IM is of aconstruction to cause so-called door-bell actuationif its mainenergizing circuit through contacts I4 and I5 of relays TR and TP iscontinuously closed at these contacts I 4 and I5, and that upon suchcontinuous closure of these contacts I4 and I5 the impulsing relay IMwould intermittently operate from` one position to the other and in eachoperation would dwell in its right-hand position much longer than itwould in its left-hand position. It is readily seen from Fig. 2 of thedrawing that such intermittent socalled door-bell actuation of theimpulsing relay IM will not take place in practice'beca1e the frontcontact I5 of the track repeater relay TP opens before the impulsingrelay IM has had an opportunity to return to its left-hand position,this is indicated by the fact'that the dashes in line 6 of Fig. 2 of thedrawing terminate after the dashes in line 9 of Fig. 2 of the drawingbegin. That is, such door-bell actuation can take place in point of timeonly between dotted lines 23 and 24 and this allows time only for oneactuation toward the right.

Having thus shown and described one rather specific embodiment oftheinvention it is desired to be understood that the particularembodiment shown has been selected for the purpose of facilitatingdescribing the underlying principles of the invention and the functionswhich the apparatusk of the invention is to perform and that theparticular embodiment illustrated has not been selected to show al1possible forms that the structure of the present invention may take andthat various changes, modifications and additions may be made, asrequired to 4meet the particular problem in practicing the invention,without departing from the spirit or scope of the invention except asdemanded by the scope of the following claims.

What I claim as new is:

1. In a railway block divided into two sections by insulating joints thefirst section of which is rst occupied by a train moving in the normaltraic direction, a track circuit for each section including a source oftrack current at the eXit end and a code following track relay at theentrance end, driven code creating means at the exit end of the secondsection for transmitting a driven code from the exit end toward theentrance end of said second section, a relatively quick acting trackrepeater relay and an impulsing relayat the entrance end of said secondsection, said impulsing relay being a two-position relay constructed toremain in its last operated position `until again operated and havingtwo windings and contacts for closing at one point an energizing circuitincluding one winding and a current source when such relay assumes thenormal position and closing the other winding in an energizing circuitincluding a current source when such relayassumes the reverse position,light retarding means associated with said impulsing relay and effectivewhen said one winding is energized, heavy retarding means associatedwith said impulsing relay effective when said other winding isenergized, said energizing circuit for said one Winding also including afront contact of said track repeater relay and a back contact of saidcode following track relay, a front contact on said track repeater relayfor repeating said driven code from Said second section into said firstsection, and contacts on said impulsing relay for connecting said codefollowing track relay of'said second section and an inverse code sourceinto the track circuit of said second secfollowing trackrel-ay or saidinverse code current tion when 4said impulsing relay .assumes its normaland reverse positionrespectively.

2. In a railway track block divided intotw `sections the first section'of which :is izirst occupied having two windings andcontacts torclosing'at one point an energizing circuit including yone winding and asource of current when vsuch relay assumes the normal position andclosing the other winding in an energizing circuit including a lcur--rent source vwhen such relay: assumes the reverse position, lightretarding meansy associated with said impulsingrelay andelective whensaid onel winding is energizedfheavy vrel'farding Ymeansv in cludingsaid light retarding means associated with said iinpulsin'g relay andeiective'when said other winding is energized, said energizing circuitfor said one winding also including a vfront contact of said track'repeater relay and a back contact of said code followingytrackrelay,.a1iront contact on said track repeater relay .for repeating saiddriven code vfrom said second sectioninto said rst section,` andcontacts'on said impulsing relay f yfor connecting said code followingtrack relay of said second section and aninverse code source into thetrack circuit of ,said second section when said impulsing relayassuinesi'ts norrnal'and re verse positionv respectively, said heavyretarding means andv said light retaldingmeans having retardingrelationships such that the inverse code impulse very closelyfollowsthetermination'of the driven code impulse and" terminatesconsiderably before the next driven code impulse begins.

. 3. In a railway track block divided into two sections py insulatingjoints# the iirst section of which is'rst occupied by 'a trainmoving inthe normal traffic direction, atrack circuit ior'each sectionl:including a source 'of' track current at the exit end and a codefollowing track relay atthe :entrance end, driven code creating meansattire exit end of the second section for intermittently `connecting'thesource of track current to the rails of `said second section to create amultiple 'impulse driven code inthe track circuit of saidsecondse'ction, a track repeater lrelay anda polar impulsing relay ofthe two-position type at the entrance end of said second section andcon-- structed to remain'in its, last operated position until' againoperated, an inverse current source, a lr'st winding for saidimpulsingrel/ay source to the track rails of said second section in response tosaid impulsingrelay assuming said rst or said second positionrespectively, means associated with .said impulsirrgrelay for slightly.retarding operation of such relay when it is energized through the.medium of said first vwinding and Eor'heavily rotar-ding operation ofsuchrelay wheny it is energized through the medium of said secondwinding, and a front `contactol said track repeater relay included yinseries with the source of track current ofthe track circuit' of saidlirst section. l

4. a railway track block divided into two sections 'by insulating jointsthe .first section of which isf'iirst occupied .by atrain moving Yin thenormal traffic direction, a vtrack circuit :for the second section ofsaid bloc-k including a Ysource of` track ycurrent at the exit end and acode .following'track relay at the entrance `end, driven code creatingmeans .at the exit end of the second section for intermittentlyconnecting the source of track current to the rails ofl said secondsection to creat-e a multiple impulse driven code in the track circuitoi said `second section, atrack repeater relay and a lpolar impulsingrelay of the two-position type at theentrance Iencl of said -secondsection, an inverse code current source, a first winding for saidimpulsing relay included in 'a circuit including a front contact of saidtrack repeater relay a back contact of said track lrelay and contacts ofsaid impulsing relay closed when such relay assumes a rst position andalso includinga source of current of a polarity to oper- .ate the relayto a second position, a secondwinding for said impulsing relay includedin a circuit including contacts of said impulsing relay closed when suchrelay assumes said second position and including a source of currentof apolarity to operate the impulsing relay to the said first posi tionoth-er contacts on saidirnpulsing relay for connecting the associatedvcode following track relay orsaidinverse Vcode current source to thetrack rails :ci said second section depending upon whether saidfimpulsing relay assumes said first or said second positionrespectively, and means associa-ted with said impulsing relay' forslightly retarding. operation of .such relay when it is enlergunedthrough themedium of vsaid rst winding and for heavily retardingoperation of such relay when itis energized through the medium yor Ysaidsecond winding.

5. In combination, a pair of track rails upon which thev impulses 'of adriven code are impressed, a code following track relay, an inverse codebattery, a track repeater' relay controlled through a viront Contact ofsai'dcode .following track relay, an .impulsing relay operated vto one'position through the medium of a first circuit inincluded iu va circuitincluding a front 'contact of v said track repeater relay a back contactof said track relayk and contacts ci .said impulsing relay,

closed when .such-impulsing relay assumesa rst position and including asource oi current of a 'cluding a source of current a iront contact ofsaid track repeater relay and a back contact offsaid.

`code following track relay, and operated to the other position throughthe medium or a secon-d circuit for `said impulsing relay including lasource` Aof current and its own' contact closed only when said impulsingrelay assumes said one position, contacts on said impulsing relay ier'connect- 'ing said code following track relay to said impulsing relayassumes said oneposition, and

ineans for retardine the operation oi said' impulsing relay to a .slightextent when said rst circuit is energized and retarding it to a greaterextent when said second circuit ls energized.

6. In combination, a pair of track rails upon which the impulses of adriven code are impressed, a code following track relay, an inverse codebattery, a track repeater relay controlled through a front contact ofsaid code following track relay, an impulsing relay operated to oneposition through the medium of a first circuit including a source ofcurrent, a front contact of said track repeater relay and a back contactof said code following track relay, and operated to the other positionthrough the medium of a second circuit including a source of current itsown contact and closed only when said impulsing relay assumes said oneposition, contacts on said impulsing relay for connecting said codefollowing track relay to said track rails when said im pulsing relayassumes said other position and for y connecting said inverse codebattery to said track rails when said impulsing relay assumes said oneposition, means foruretarding the operation of said impulsing relay to aslight extent when said rst circuit is energized and retarding it to agreater extent when said second circuit is energized, a track sectionadjacent said pair of track rails having a track circuit including asource of track current, and a front contact of said track repeaterrelay included in series with said source of track current in saidadjacent track circuit for repeating said driven code into said adjacenttrack circuit.

7. In combination, a pair of track rails, a code following track relayperiodically energized under favorable traliic conditions, an inversecode battery, a track repeater relay controlled through a front contactof said code following track relay, an impulsing relay operated to oneposition through the medium of a rst circuit including a front contactof said track repeater relay and a back contact of said code followingtrack relay and a source of current, and operated to the other positionthrough the medium of a second circuit including a source of current andits own contact closed only when said impulsing' relayassumes said oneposition, contacts on said impulsing relay for connecting said codefollowing track relay to said track rails when said impulsing relayassumes said other position and for connecting said inverse codebattery-to said track rails when f said impulsing relay assumes said oneposition, and means for retarding the operation yof said impulsing relayto a slight extent when said first circuit is energized and retarding itto a greater extent when said second circuit is energized, a tracksection adjacent said pair ofV track rails but insulated therefrom andprovided with a track circuit having a source of track current at theadjacent end, and a front contact of said track repeater relay includedin series with said source of track current.

8.l In combination, a pair of track rails, a code following track relayperiodically energized under favorable traiiic conditions, an inversecode battery, a track repeater relay controlled through a front contactof said code following track relay, an

. impulsing relay operated to one position through the medium of a firstcircuit including a source of current a front contact of said trackrepeater relay and a back Contact of said code following track relay,and operated to the other position through the medium of a secondcircuit including a source of current its own contact and closed onlywhen said impulsing relay assumes said one position, contacts on saidimpulsing relay for connecting said code following track relay to saidtrack rails when saidimpulsing relay assumes said other position and forconnecting said inverse code battery to said track rails when saidimpulsing relay assumes said one position, and a rectier and aresistance unit included in 'series therewith and included in multiplewith a winding of said impulsing relay withthe rectifier so poled thatvery little current flows therethrough when said rst circuit isenergized but a large amount of current flows therethrough when said'second circuit is energized to retard the operation of said impulsingrelay to a slight extent and a great extent respectively as said rst andsaid second circuit are energized.

9. In a driven coded and an inverse coded track circuit, a pair of trackrails, a code following track relay at times connected across the trackrails at one end, means for applying a driven code consisting ofperiodic impulses of current across the track rails at the other end, arepeater track relay controlled through a front contact of said codefollowingtrack relay, an electro-responsive device having two windingsand constructed to be operated quickly to one position when one fwindingis momentarily energized and operated less quickly to the oppositeposition when the other winding is momentarily energized, a circuit formomentarily energizing said one winding including a source of current afront contact of said repeater track relay and a back contact of `saidcode following track relay, a circuit for momentarily energizing saidother winding including a source of current, a contact closed when saidelectro-responsive device assumes said one position, an inverse currentsource, and contact mechanism operated by saidelectro-responsive devicefor connecting said code following track relay across the track railswhen said elec- 40 tro-responsive device assumes said other position andconnecting said inverse current source across the track rails when saidelectro-responsive device assumes said one position.

10. In a driven coded and an inverse coded track circuit, a pair oftrack rails, a code following track relay at times connected across thetrack rails at one end, means for applying a driven code consisting ofperiodic impulses of current across the track rails at the other end, arepeater track relaycontrolled through a front contact of said codefollowing track relay, an electro-responsive device having two windingsand constructed to be operated quickly to one position when one windingis momentarily energized and operated less quickly to the oppositeposition when the other winding is momentarily energized, a circuit formomentarily energizing said one winding including a source of current afront contact of said repeater track relay and a back contact of saidcode following track relay, a circuit for momentarily energizing saidother winding including aV source of current a contact closed when saidelectro-responsive device assumes said one position, an inverse currentsource, contact mechanism operated by said electro-responsive device forconnecting said code following track relay across the track rails whensaid electro-responsive device assumes said other position andconnecting said inverse current source across the track rails when saidelectro-responsive device assumes said one position,v and coderesponsive means controlled by said repeater track relay, f

" I MARCIAN A. SCHEG.

